Solvent refining of hydrocarbon oil



Patented Oct. 4, 1938 UNITED STATES PATT FFIQE Louis A. Clarke,Fishkill, N. Y., assignor to The Texas Company, New York, N, Y., acorporation of Delaware No Drawing. Application June 5, 1937, Serial No.146,587

2 Claims.

This invention relates to refining hydrocarbon oil, and moreparticularly to refining mineral oil by solvent extraction.

The invention contemplates the solvent ex- 5 traction of hydrocarbon oilwith a selective solvent comprising resorcinol monoacetate to separatethe oil into fractions having different characteristics.

I have discovered that resorcinol monoacetate is particularly suitableas a solvent refining agent for mineral oil, and especially for therefining of lubricating oil fractions derived from petroleum.

I have also discovered that this solvent, when used for treating minerallubricating oil, permits obtaining a high yield of high viscosity indexoil having a good color as well as other desirable characteristics. Inthis respect, it is superior to many of the known selective solvents;that is, it is possible to obtain high viscosity index oil of good colorwithout substantially sacrificing the yield.

Treatment of the oil with the solvent may be effected by stage orcontinuous countercurrent contact. In either case, the mixture of oiland solvent is separated into extract and raflinate phases. The extractphase comprises the socalled naphthenic or low viscosity indexconstituents of the oil dissolved in the main body of the solvent, Whilethe raffinate phase comprises the so-called parafiinic or high viscosityindex constituents of the oil mixed with a small portion of the solvent.

The two phases are separated, and the solvent removed therefrom bydistillation or by some other means, for example, washing or displacingthe solvent from the oil by contact with some other liquid or solvent.

As a specific example, a lubricating oil distillate obtained fromMid-Continent crude, and having the tests indicated below was extractedwith resorcinol monoacetate, using three parts of solventto one part ofdistillate, and at a temperature of about 237 F. The mixture wasseparated into extract and rafiinate phases, and the rafiinate phase,upon removal of the solvent liquid, comprised about 88% by volume of theoriginal distillate.

The tests on the distillate before extraction, and on the resultingrafiinate oil, were as follows:

50 Distillate Raffinate From the foregoing, it is observed that arelatively high yield of raflinate was obtained, namely, 88%, having aviscosity index of 70, as compared with a viscosity index of 5'7 for theoriginal distillate.

Oil of still higher viscosity index, of course, can 5 be obtained byaltering the solvent proportions and the extraction temperature, inwhich case a somewhat lower yield of raffinate, corresponding .to thehigher viscosity index, would be obtained.

It is, therefore, contemplated that extraction temperatures, eitherbelow or above that' specified above, may be used. Likewise, the solventdosage may be varied as, for example, from one to four parts of solventto one of oil. These factors can be varied, depending upon the nature ofthe oil undergoing treatment as well as upon the degree of extractiondesired.

While a distillate oil has been referred to above in the specificexample, it is, of course, contemplated that residual fractions may alsobe treated with the solvent. The solvent is also useful in theextractive treatment of other petroleum fractions as, for example,naphtha, kerosene, etc.

When treating lubricating oil stock, the oil may be diluted with asuitable diluent such as a lowboiling petroleum hydrocarbon, and thedilute mixture subjected to extraction with the solvent.

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

1. In the refining of hydrocarbon oil containing 35 relativelyparafi'inic and relatively non-paraflinic constituents to separate theoil into fractions re- 4 spectively rich in paraihnic and non-parafiinicconstituents, the method which comprises mixing the oil with a selectivesolvent comprising resorcinol monoacetate, forming anextract phasecontaining non-paraifinic constituents dissolved in the solvent and arafiinate phase comprising parafiinic constituents of the oil, andseparating the two phases.

2. The method of treating mineral lubricating oil containing relativelyparafiinc and relatively non-paraifinic constituents to separate the oilinto fractions respectively rich in paraffinic and nonparafilnicconstituents comprising mixing the oil with a selective solventcomprising r-esorcinol monoacetate, forming an extract phase containingnon-paraffinic constituents dissolved in the solvent and a rafiinatephase comprising paraffinic constituents of the oil, and separating thetwo phases.

' LOUIS A. CLARKE.

